The present invention refers to a magnetic liquid seal for an antifriction bearing and to a magnetic liquid return feature of the seal and bearing.
One liquid seal embodiment is known from Federal Republic of Germany Published Application OS 3,824,104. In that case, both the magnetic liquid seal and a pre-seal element on the axial side of the seal closer to the bearing rollers face a set back section of the inner ring of the bearing. This seal is highly expensive particularly for the manufacture of its inner ring. The shoulder of the inner ring must be made in stepped-down shape, i.e. two surfaces which are arranged displaced with respect to each other must be machined both upon the turning and upon the grinding. Another disadvantage is that the pre-seal must be precisely positioned axially in order, on the one hand, to obtain the desired sealing action and, on the other hand, to prevent the resting of the pre-seal against the mating bearing race. Such resting produces an impermissible increase in the moment of friction in many fields of use. This requires an exact arrangement and exact axial positioning of the notch, particularly a notch formed in the inner ring, into which a lip of the seal extends. Furthermore, the separate pre-seal must also be arranged in an additional holding groove in the outer ring. This also makes installation of the seal and of the bearing difficult.